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ANUNG KURNIAWAN Question

2012-01-01T22:26:00.000-08:00

1. what is the meaning about cable STP?

answer :
STP cable is one type of cable used in computer networks. STP cable is more resistant to interference caused the position of the bent wire.

2. transmission medium in a computer network consisting of quided and unguided. explain the difference of the two?

answer :

guided is end to end when is provides a direct connection between two devices and share the same media.

unguided is a medium that provides a means to transmit electromagnetic wawes .

wide area network (WAN)

2011-11-14T06:01:00.000-08:00

wide area network (WAN) is a telecommunication network that covers a broad area (i.e., any network that links across metropolitan, regional, or national boundaries). Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations. In essence this mode of telecommunication allows a business to effectively carry out its daily function regardless of location.

This is in contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.

Design options

The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. However, in terms of the application of computer networking protocols and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different LANs, WANs and other localised computer networking architectures. This distinction stems from the fact that common LAN technologies operating at Layer 1/2 (such as the forms of Ethernet or Wifi) are often geared towards physically localised networks, and thus cannot transmit data over tens, hundreds or even thousands of miles or kilometres.

WANs necessarily do not just connect physically disparate LANs. A CAN, for example, may have a localised backbone of a WAN technology, which connects different LANs within a campus. This could be to facilitate higher bandwidth applications, or provide better functionality for users in the CAN.

WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.

Academic research into wide area networks can be broken down into three areas: mathematical models, network emulation and network simulation.

Performance improvements are sometimes delivered via wide area file services or WAN optimization.

LAN (local area network)

2011-11-14T05:49:00.000-08:00

Local area network is a computer network whose network covers only a small area, such as campus computer networks, buildings, offices, in homes, schools or smaller. Today, most LAN technology based on IEEE 802.3 Ethernet switch using the device, which has a data transfer speed 10, 100, or 1000 Mbit / s. In addition to Ethernet technology, the current 802.11b technology (or so-called Wi-Fi) is also often used to form the LAN. Places that provide LAN connectivity with Wi-Fi technology called hotspots.

On a LAN, each node or computer has its own computing power, in contrast to the concept of terminal dump. Each computer can also access resources on the LAN in accordance with the perm
issions that have been set. These resources can be data or devices such as printers. On a LAN, a user can also communicate with other users by using the appropriate application.

In contrast to Wide Area Networks or Wide Area Network (WAN), the LAN has the following characteristics:

- Having a higher data rapidly

- Includes a narrower geographical region

- Does not require telecommunications lines leased from telecom operators

Usually one of the computers on the network computer will be used to manage all servers in the network system.

Network address translation (NAT)

2011-11-14T05:34:00.000-08:00

Network address translation is a method to connect more than one computer to the Internet network by using a single IP address. Much use of this method due to the limited availability of IP addresses, the need for safety (security), and the ease and flexibility in network administration.

IP addresses

Currently, the widely used IP protocol is IP version 4 (IPv4). With a length of 4-byte address means that there are 2 to the power 32 = 4,294,967,296 available IP addresses. This amount is theoretically the number of computers that can directly connect to the internet. Because of this limitation of most ISPs (Internet Service Provider) will only allocate one address for one user and this address is dynamic, in the sense of a given IP address will be different each time a user to connect to the internet. This will make it difficult for businesses to lower middle class. On the one hand they need more computers are connected to the internet, but on the other hand only one available IP address, which means there is only one computer that can connect to the internet. This can be overcome with the NAT method. With a NAT gateway that runs on one computer, one IP address can be divided into several other computers and they can connect to the internet simultaneously

Security

When a computer connected to the internet, the computer can not only access, for example to the server a particular site, but the computer is also very likely to be accessed by other computers are also connected to the internet. If misused, it can be very dangerous. Important data can be viewed or even stolen by people who are irresponsible. NAT will automatically give protection as well as a firewall to only allow connections from the network. This means that a network security level will increase, because of possible connections from outside to inside the network to be relatively very small.

Network Administration

With NAT, a large network can be broken down into smaller networks. Small parts that each have a single IP address, so we can add or reduce the number of computers without affecting the overall network. In addition, the modern NAT gateway DHCP server exists that can automatically configure the client computer. This is very advantageous for network admins because to change the network configuration, the admin just need to change on a computer server and these changes will happen on all client computers. Besides the NAT gateway is able to limit access to the internet, is also able to record all traffic, and from the Internet. Overall, with all the advantages that the NAT gateway, network admin would be very helpful in performing his duties.

types of NAT :

1.full cone NAT

2.Restricted cone NAT

3.Port restricted cone NAT

4.Symmetric NAT

Routing static and Routing dynamic

2011-11-14T05:09:00.000-08:00

Routing Static

a routing table creation manually. Static routing is useful for simple networks where routers only use a few pieces only and is useful for saving bandwidth usage. Manually point is if my friend as a network administrator, type in certain commands to create a static IP routing as an example, suppose I type the following command:
router (config) # ip route network_destination_id subnet_mask default_gateway [administrative_distance]
The following description of the command that I created above:

network_destination_id is the network address of the destination
subnet_mask is the subnet mask of the destination network.
default_gateway is the gateway IP address, router address is usually directly related.
administrative_distance is the value 0-255 given to routing. Increase low value given the high increase its usefulness. If the value is not given then a default value will be used. The default value for directly connected (C) = 0 and statically connected (S) = 1.

How to create a static routing for Router 1 to the destination network ID 192.168.20.0 and subnet mask 255.255.255.0 is by typing a command like the example above:

router1 (config) # ip route 192.168.20.0 255.255.255.0 192.168.10.11

router1 # sh ip route

Routing Dynamic

use a routing protocol that makes routing tables automatically if the network topology changes. Dynamic routing in general can be divided into two categories. Distance vector and link state routing protocol, each of which consists of a variety of routing protocols.
RIP (Routing Information Protocol) is the simplest protocol to include the type of distance vector. RIP uses the number of jumps (hop count) as a metric with a maximum of 15 hops. So hop count to-16 can not be achieved and the router will give an error message "destination is unreachable" (objective not achieved). RIP routing tables list is updated every 30 seconds, while the default administrative distance for RIP is 120.
To implement the RIP on the router, the following command:
router (config) # router rip
To apply RIP to a specific network address, the following command:
router (config-router) # network network_id

How to configure RIP to Router 1 as brikut:
router1 (config) # ip routing
router1 (config) # router rip
router1 (config-router) # network 215.10.20.0
router1 (config-router) # network 215.10.10.0
router1 (config-router) # exit
router1 # write memv

subnetting/subnet mask

2011-11-14T04:54:00.000-08:00

The subnet mask is the term information technology in the English language that refers to the 32 bit binary number that is used to distinguish the network ID with the host ID, showing the location of a host, whether located on a local network or external networks.

RFC 950 defines the use of a subnet mask which is also called as an address mask as a 32-bit value that is used to distinguish the network ID of the host ID in an IP address. The bits of the subnet mask is defined, are as follows:

- All bits are intended to be used by the network ID is set to a value of 1.
- All bits are intended to be used by the host ID is set to a value of 0.

Every host on a network that uses TCP / IP requires a subnet mask despite being on a network with one segment only. Whether it's the default subnet mask (which is used when using class-based network ID) or a customized subnet mask (which is used when making a subnet or supernet) must be configured in each node TCP / IP.

Representation of Subnet Mask

There are two methods that can be used to represent the subnet mask, namely:

Dotted Decimal Notation
The network prefix length notation

Dotted Decimal

A subnet mask is usually expressed in dotted decimal notation (dotted decimal notation), as well as the IP address. After all bits are set as the network ID and host ID, the 32-bit value will be converted to dotted decimal notation. It should be noted, that although it is represented as a dotted decimal notation, the subnet mask is not an IP address.

The default subnet mask is based on IP address classes and used in the TCP / IP network that is not divided into several subnets. The table below mentions some of the default subnet mask by using dotted decimal notation. The format is:

<alamat www.xxx.yyy.zzz> IP, mask <subnet www.xxx.yyy.zzz>

Classes address Subnet mask (binary) subnet mask (decimal)
Class A 255.0.0.0 11111111.00000000.00000000.00000000
Class B 255.255.0.0 11111111.11111111.00000000.00000000
Class C 255.255.255.0 11111111.11111111.11111111.00000000

Keep in mind, that the value above the default subnet mask can be customized by the network administrator, during a process of distribution networks (subnetting or supernetting). For example, 138.96.58.0 address is an identifier of a class B network that has been divided into several subnets by using 8-bit numbers. Eight bits are used as the host ID will be used to display the network ID that has been divided into subnets. Subnet used is a total of 24 bits (255.255.255.0) which can be used to define a custom network ID. Network identifier that has been such a subnet and the subnet mask used will then be displayed using the following notation:

138.96.58.0, 255.255.255.0

Representation of prefix length (prefix length) of a subnet mask

Because the network identifier bits must always be chosen in a form from the adjacent high-order bits, then there is a means used to represent a subnet mask by using the bits that define the network ID as a network prefix using network prefix notation as listed in the table below. Notation network prefix notation also known as Classless Inter-Domain Routing (CIDR) which is defined in RFC 1519. The format is as follows:

/ <number Bits are used as network identifier>

Classes address Subnet mask (binary) subnet mask (decimal) Length Prefix
Class A 255.0.0.0 11111111.00000000.00000000.00000000 / 8
Class B 255.255.0.0 11111111.11111111.00000000.00000000 / 16
Class C 255.255.255.0 11111111.11111111.11111111.00000000 / 24

For example, a class B network ID of 138.96.0.0 with a subnet mask of 255.255.0.0 can be represented in prefix length notation as 138.96.0.0/16.

Because all hosts within the same network using the same network ID, then all hosts within the same network must use the same network ID as defined by the subnet mask the same. For example, the notation is not the same as the notation 138.23.0.0/16 138.23.0.0/24, and both networks are not in the same address space. Network ID 138.23.0.0/16 has a range of valid IP addresses ranging from 138.23.0.1 to 138.23.255.254, while network ID 138.23.0.0/24 only have a range of valid IP addresses ranging from 138.23.0.1 to 138.23.0.254.

Determine the address of the Network Identifier

To determine the network ID of an IP address by using a subnet mask, can be done using a mathematical operation, namely by using a comparison of AND logic operation (AND comparison). In an AND comparison, the value of the two things that will compare the two is true only when the item is true, and to false if one of them false. By applying this principle into bits, a value of 1 will be obtained if the two bits that are comparable to 1, and the value 0 if there is one among the comparable value is 0.

This will perform a comparison with the logical AND operation using 32-bit IP address and a 32-bit subnet mask, known as the bitwise logical AND operation of comparison. The results of bitwise operations to subnet mask IP address that is called a network ID.

Example:

IP address 10000011 01101011 10100100 00011010 (131 107 164 026)
Subnet Mask 11111111 11111111 11110000 00000000 (255 255 240 000)
-------------------------------------------------- ----------------
Network ID 10000011 01101011 10100000 00000000 (131 107 160 000)
Table Creation subnet

subnetmask is called the classes are grouped known three classyaitu:

1. Class A, is all the IP numbers that have a subnetmask 255.0.0.0

2. Class B, is all the IP numbers that have a subnetmask 255.255.0.0

3. Class C, is all the IP numbers that have a subnetmask 255.255.255.0

Netmask combination of IP and this is the computer addressing is used. Both of these can not escape. So the writing is usually as follows: IP: 202.95.151.129 Netmask: 255.255.255.0

IP ADDRESS

2011-11-14T04:20:00.000-08:00

IP Address is the address given to the network and network equipment that uses the protocol TCP / IP. IP Address consists of 32-bit binary numbers which can be written as four decimal numbers separated by a dot such as 192.16.10.1. Therefore, the IP protocol is the most widely used protocol for forwarding (routing) information in a computer network with one another, then we must truly understand that IP address. But understanding the IP addresses and subnetting often somewhat confusing users. Therefore, in here will be described step by step the concept of an IP address with the hope that you can understand how to use it well. IP Address consists of two parts, namely the network ID and host ID, which determines the address of the network ID and host ID determines the network of network equipment. Therefore, the IP address to give the full address of a network equipment and network address where the equipment is located. This is the same proverbial with the provision of residential address of the house where we are.

Implementation 802 xx

2011-11-14T04:01:00.000-08:00

The IEEE 802 Standard comprises a family of networking standards that cover the physical layer specifications of technologies from Ethernet to wireless. IEEE 802 is subdivided into 22 parts that cover the physical and data-link aspects of networking. The better known specifications (bold in table below) include 802.3 Ethernet, 802.11 Wi-Fi, 802.15 Bluetooth/ZigBee, and 802.16.

"Grandaddy" of the 802 specifications. Provides asynchronous networking using "carrier sense, multiple access with collision detect" (CSMA/CD) over coax, twisted-pair copper, and fiber media. Current speeds range from 10 Mbps to 10 Gbps.

802.11 Wi-Fi Wireless LAN Media Access Control and Physical Layer specification. 802.11a,b,g,etc are amendments to the original 802.11 standard. Products that implement 802.11 standards must pass tests and are referred to as "Wi-Fi certified."

802.15 :

=> 802.15.1 Bluetooth Short range (10m) wireless technology for cordless mouse, keyboard, and hands-free headset at 2.4 GHz.

=> 802.15.4 ZigBee Short range wireless sensor networks

802.16 Wireless Metropolitan Area Networks This family of standards covers Fixed and Mobile Broadband Wireless Access methods used to create Wireless Metropolitan Area Networks (WMANs.) Connects Base Stations to the Internet using OFDM in unlicensed (900 MHz, 2.4, 5.8 GHz) or licensed (700 MHz, 2.5 – 3.6 GHz) frequency bands. Products that implement 802.16 standards can undergo WiMAX certification testing.

All the 802.11 specifications use the Ethernet protocol and Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) for path sharing. The original modulation used in 802.11 was phase-shift keying (PSK). However, other schemes, such as complementary code keying (CCK), are used in some of the newer specifications. The newer modulation methods provide higher data speed and reduced vulnerability to interference.

Transmission media

2011-11-14T03:49:00.000-08:00

What is Transmission media

Transmission media is a media that connects between the sender and receiver of information (data), because of the distance, then the first data is converted into code / cue, and this signals to be manipulated in various ways to be converted back into data.

Usefulness of transmission media

Transmission mediaused in some electronic equipment to connect between the sender and receiver to be able to exchange data. Some electronic devices, such as telephones, computers, television, and radio transmission media need to be able to receive data. As in the receiver, the transmission mediaused to connect two phones are wired. Every electronic device has a transmission mediawhich vary in data delivery.

Characteristics of transmission media
Characteristics of transmission media is dependent on:
- Types of electronic devices
- Data used by electronic devices such
- The level of effectiveness in the delivery of data
- Size of data transmitted
This type of transmission media
Guided Transmission Media
Guided transmission media or guided transmission mediais a network that uses a cable system.

Twisted Pair Cable
Twisted pair cable or twisted pair cable consists of two conductors are coupled with the aim to reduce or eliminate interference from the outside like lektromagnetik electromagnetic radiation from unshielded twisted-pair cable (UTP), and crosstalk that occurs between adjacent wires. There are two kinds of Twisted Pair Cable, the STP and UTP cable. STP cable (Shielded Twisted Pair) is one type of cable used in computer networks. This cable contains two pairs of wires (four wires) of each twisted pair. STP cable is more resistant to interference disebebkan wires are bent position. At STP cable attenuation to increase at high frequencies giving rise to crosstalk and noise signals. UTP (Unshielded Twisted Pair) is widely used in computer network installation. This cable contains four pairs of twisted-pair wires each (twisted). These cables are not equipped with protective (unshilded). UTP cable is easy to install, small size, and price is cheaper than other types of media. UTP cables are particularly vulnerable to the effects of electrical interference from the surrounding media.

Coaxial Cable
Coaxial cable is a type of cable that uses two conductors. These cables are widely used for transmitting high frequency signals began to 300 kHz and above. Because of its ability to deliver such high frequencies, then the transmission system using coaxial cable has a large enough channel capacity. There are several types of coaxial cable, which is thick coaxial cab le (having a large diameter) and thin coaxial cable (has a smaller diameter). Excellence is the coaxial cable can be used to channel information for up to 900 telephone channels, can be planted in the ground so that the lower maintenance costs, because it uses the small isolation cover the possibility of interference with other systems. The downside is the coaxial cable attenuation has a relatively large so that for long-distance relationship repeater-repeater should be installed, if the cable is installed above ground, vulnerable to physical disturbances that can result in disconnection.

Fiber Optic
Fiber optics is the transmission line made of glass or plastic that is used to transmit light signals from one place to another. Based on the transmission mode optical fiber that is used consist of Step Index Multimode, Graded Index Multimode and singlemode Step Index. Advantages of fiber optics is cheaper, more streamlined shape, a larger transmission capacity, less signal is lost, the data is converted into light signals resulting in faster, less power required, and non-flammable. Weaknesses include the cost of optical fiber is expensive for the equipment, requiring conversion of electrical data into light and vice versa is complicated, requiring special equipment in use and installation procedures, as well as for complex repairs require skilled manpower in this field. In addition to an advantage, its not conduct electricity is also a weakness because it requires an external power tools.
Unguided Transmission Media
Unguided transmission media or not the transmission mediais a network that uses guided wave system.

Microwaves
Microwave (microwave) is a form of radio that uses high frequency (in units of gigahertz), which covers the area UHF, SHF and EHF. Microwaves are widely used in the MAN network system, internet cafe and internet service provider (ISP). The advantage of using microwaves is the acquisition between the tower is not so necessary, can carry large amounts of data, low cost because each tower antenna does not require a large area, high frequency or short wave because it only requires a small antenna. Weaknesses microwaves are susceptible to weather such as rain and easily influenced planes flying over it.

Satellite
The satellite is transmitting media whose main function receives a signal from the earth station and forward it to another earth station. Satellites orbiting at an altitude of 36,000 km above the Earth has an orbital angular velocity equal to the orbital velocity of the earth. This causes the satellite to be relatively stationary position of the Earth (geostationary), if the satellites are orbiting above the equator. In principle, by placing three geostationary satellites in the right position to reach the entire surface of the earth. Advantages satellite is cheaper than by holding an intercontinental cable, can reach the Earth's surface area, including remote areas with low population, the growing telecommunications traffic between continents makes satellite systems commercially attractive enough. The drawback is the limited technology for the use of satellite antennas with a large size, investment and insurance costs are still expensive satellites, atmospheric losses are great for frequencies above 30 GHz limit the use of the carrier frequency.

Radio waves
Radio waves are the transmission mediathat can be used to transmit voice or data. Excess transmission of radio waves are able to send a signal to the position of arbitrary (not necessarily straight) and it is possible in a state of motion. Frequency of use between 3 KHz to 300 GHz. The radio waves used on VHF and UHF bands: 30 MHz to 1 GHz includes an FM radio and UHF and VHF television. Used for digital data communication packet radio.

Infra red

Infrared is used for communication at close range, with a speed of 4 Mbps. In its use to control remotely, for example, the remote control at the television and other electronic devices. Advantages infrared is immune to radio interference and elekromagnetik, infrared easy to make and inexpensive, easy installation, easily removable, higher security than radio waves. The downside is infrared finite distance, can not penetrate the wall, there should be a straight path from the sender and receiver, can not be used outdoors because it will be disturbed by the light of the sun.

NETWORK APPLICATION

2011-10-03T08:28:00.000-07:00

Networking Software Applications and Tools
Network software applications using the Internet or other network infrastructure hardware to perform useful functions.

Macintosh Network
Windows Firewall Software
Network Operating System
Gaming Network
FTP Client and Server
Network Ping (6)
Microsoft Internet Explorer
Linux Networking (6)
Network Programming

INTERNET CONNECTIVITY APPLICATIONS

• Web-server applications (JAVA / PERL-CGI)
• Download file
• Automatic data distribution
• Monitoring and control
• Both real-time and store-and-forward data available architectures
• Connectivity: Wi-Fi 802.11a / b, 2-way pager / cell network, low-cost radio, dial-up services

Top Internet Connection Sharing Software

Combination the functions of a proxy server and firewall, software products provide a more secure Internet connection sharing on a LAN.

P2P File Sharing Software Programs

Free P2P clients allow easy swapping of music, videos and other files over the Internet.
Internet Remote Access Software
Remote access programs that support the software connects to the PC in the home network. Remote access software allows you to retrieve data when not at home or assist family members with network problems.

VNC – Virtual Network Computing

VNC (Virtual Network Computing) is a popular technology for remote desktop sharing. VNC allows viewing a desktop from one computer to be viewed and controlled remotely via a network connection.

Firmware – Router Firmware
In a home network router, firmware is embedded software that controls the logic device. Router firmware implements a portion of a wired or wireless networking protocols and security mechanisms.

About the OSI and TCP / IP

2011-10-03T08:02:00.001-07:00

OSI (Open Systems Interconnection)

OSI is a conceptual model consisting of seven layers, each layer has a different function. OSI was developed by the international agency that is ISO (International Organization for Standardization) in 1977.

The function of each layer of the OSI:

1. Physical Layer

Physical Layer is the layer that very simple, relating to electrical (and optical) connections between devices. This layer Serves to define the network transmission media, signaling method, synchronization bits, network architecture (such as Ethernet or Token Ring), network topology and pengabelan. In addition, this level also defines how the Network Interface Card (NIC) can interact with the media cable or radio.

2. Data-link Layer

Data link layer is responsible at the end of the package binary data derived from a higher level into discrete packets before the physical layer. Will send frames (block of data) via a network. Protocol on the data-link layer is Ethernet (802.2 & 802.3), Tokenbus (802.4) and Tokenring (802.5).

3. Network Layer

Network layer provides routing functionality so that packets can be sent out from the local network segment to a destination that is on a network other.

Some network layer functions:
- Divide the binary data stream into discrete packets with a certain length
- Detect Error
- Fix error with resend the corrupted packet
- Controlling the flow

4. Transport Layer
Transport layer is the center of the fashion-OSI. Serves to break down data into packets of data and provide the serial number of the packages that can be rearranged on the side of the goal as it arrives.

5. Session Layer
This layer coordinates communication between the layer entities they represent. Serves to define how the connection can be established, maintained, or destroyed. In addition, at this level also performed name resolution. Some of the protocol at this layer: NETBIOS: a session interfaces and protocols, developed by IBM, which provides service to the presentation layer and application layer. NETBEUI, (NETBIOS Extended User Interface), a development of NETBIOS used in micro ** oft networking products, such as Windows NT and LAN Manager. ADSP (AppleTalk Data Stream Protocol). PAP (Printer Access Protocol), which is found on a Postscript printer to access the AppleTalk network.

6. Presentation Layer
Serves to translate the data to be transmitted by the application into a format that can be transmitted over the network. The protocols are in this level is redirektor software (redirector software), such as Workstation service (in Windows NT) and Network shell (a sort of virtual network computing (VNC) or Remote Desktop Protocol (RDP).

7. Application Layer
Application Layer is the primary interface between applications running on one computer and network resources that require access to it. Application layer is the layer where the user will operate it, protocols such as FTP, telnet, SMTP, HTTP, POP3 is the Application layer.

TCP / IP (Transmission Control Protocol / Internet Protocol)

TCP / IP is a data communications standard used by the Internet community in the process of exchanging data from one computer to another computer on the network the Internet. TCP / IP is an open networking standard that is independent of physical network transport mechanism used, so it can be used anywhere.

The function of each layer in the TCP / IP:
- Physical Layer
Bottom layer is a layer that defines the physical quantities such as the communication medium, voltage, current, etc.. TCP / IP is flexible so it can integrate the various networks with the physical medium is different.

- Network Access Layer
Has the distribution function set data frames on the physical media used reliably. This layer usually provide service for the detection and correction of errors of data transmitted. Some examples of protocols used at this layer is X.25 public networks, Ethernet for networking Etehernet, AX.25 for packet radio networks, etc..

- Internet Layer
Having such a function at the Network Layer of the OSI that defines how the relationship can occur between two parties who are on different networks. In this layer duty to ensure that a packet is sent to find the goal wherever located. Therefore, this layer has a particularly important role in realizing the vast territory covering internetworking (Internet worldwide).

Some of the important tasks at the Internet layer are:
• Addressing
which complement each datagram to the Internet address of the
purposes. This protocol addresses the known IP Address.
• Routing
Determine to which datagram will be sent in order to achieve the desired goals. This function is the most important functions of the Internet Protocol (IP). Routers on the network TCP / IP is very crucial in the delivery of datagrams from the receiver to the destination.

- Transport Layer
Function in defining the ways to perform data transmission between end to end in a reliable host. This layer ensures that the data received with the data that is sent to the sender.

Some essential functions include:
Flow Control
Delivery of data that has been broken down into packets must be arranged in such a way so that the sender not to transmit data at speeds that exceed the ability of recipients to receive the data.
Error Detection
Sender and receiver also complement the data with some information that could be used to check the data transmitted is free from error. If found errors in the received data packet, the receiver will not receive the data. Sender will retransmit data packets that contain errors earlier.

- Application Layer
Serves to define applications that run on the network. Protocols at this layer example is SMTP (Simple Mail Transfer Protocol) for sending e-mail and FTP (File Transfer Protocol) to transfer files.

Differences of windows server and linux server

2011-10-03T07:51:00.000-07:00

WINDOWS SERVER HOST ING

Window, similar to your personal computer, Microsoft's operating system is commercially owned. Its main benefit is that it can also run Microsoft software such as Access and MS SQL databases.

WINDOWS SECURITY:

Because it is a commercial operating system, it could take a little longer in fixing some security issues (often with the release of the security package) while they usually must be made available through Microsoft.

LINUX SERVER HOSTING

Linux is an open source system that freely circulating, which makes it very cost-effective for the host to provide, maintain, and operate. It also has a very strong position for both speed and stability. It is accepted that the best part of the site that hosts basically the Linux operating system.

LINUX SECURITY:

Although Linux and Windows can try to deal with both hacking, arguing that Linux is open source, patches to close security holes are implemented very quickly because so many people contribute to making it better every day.

The meaning of hierarchy in the tree topology

2011-10-01T04:24:00.000-07:00

Network Topology Tree (Tree) network topology is referred to as a multilevel network topology. This topology is typically used for interconnection between the central with a different hierarchy. For the lower hierarchy depicted in locations with low and growing up had a higher hierarchy. This type of network topology suitable for use on a computer network system.

In tree networks, there are several levels of nodes (node). Central or higher level node, another node can set a lower level. Data sent to the central node first. For example to move from computer to the komputer node node-3-7 as well as in the figure, the data must pass through node-3, 5 and node-6 before ending at the node-7.

The excellence of tree network model like this is, can the formation of a group that required at all times. For example, companies can form a group consisting of terminal accounts, as well as in the other group formed for the sale terminals. The weakness is, if the node that is higher then does not work, then the other group who are below it eventually also became ineffective. The workings of a tree network is relatively slow.

the differences in lan, man, and wan

2011-10-01T04:11:00.000-07:00

Ø Local Area Network (LAN),

Is a privately owned network within a building or campus-sized to several kilometers.

LAN often used to connect personal computers and workstations in a corporate office or factories in order to use shared resources (resouce, such as printers) and exchange information.

Ø Metropolitan Area Network (MAN)

basically a LAN version of the larger and usually use the same technology to the LAN. MAN can include corporate offices are located adjacent or also a town and can be used for private purposes (private) or public. MAN capable of supporting data and voice, even may be associated with cable television networks.

Ø Wide Area Network (WAN)
the range covers a wide geographical area, often covering a country or even continent. WAN consists of a collection of machines that aim to run the programs (applications) user.

What sets it apart :
1. a distance

2. Speed data transfer

for Ex: LAN has a limited area but has a 2 KM Sampa 2 MBPS transfer rate, while the WAN has a range up to thousands "of KM but possessed transfer rate up to 64kbps

Transmission data on topology

2011-09-30T23:01:00.000-07:00

Transmission of the logical topology can be grouped into two:

1. Logic Bus topology (tree)

Transmission of data through each workstation on the network. Each workstation using the address to determine whether the workstation should respond terdebut transmission. In a bus topology every time the logic of each workstation on the network can receive the transmission. This is due, in a logical bus topology, each workstation using the same line to send and receive data.

2. Logical ring topology (tree)

In this topology transmission of data is done from a workstation to the next workststion. Data transmission will be great if the physical topology ring is used too. One way to determine whether the logical topology of a network using a ring is to see if the data receiver circuit and a series of separate data sender. If separate then the workstation functions as a repeater and may be logically connected with the ring topology.

computer network topology

2011-09-26T06:58:00.000-07:00

Topology is described to the structure of a network and how a network is designed. This is very closely associated with the access methods and delivery media are used. Topology that is very dependent on the location geofrapis of each terminal, the quality control is needed in communication or messaging, as well as the speed of data transmission.

the definition of topology is divided into two:

- the physical topology (physical topology) that indicated the position of the physical cabling

- logical topology (logical topology) is to shows how accessible by the host.

The physical topology is used in building such a network is :

1. Point to Point

This network is a network of point to the most simple but can be widely used. This is a simple network, so it is often not considered as a tissue but only an ordinary communication. In this case, both nodes have the same level position, so that any node can initiate and control the relationship in the network. Data sent from one node other conclusion directly as a receiver, for example between the terminals with the CPU.

view point to point network :

2. Star Network

In a star configuration, some existing equipment will be connected into a central computer. Existing controls will be centered at one point, such as workload and adjust the settings of existing resources. All links must be associated with the center if you want to distribute any other conclusion that the intended data. In this case, when the center was down, then all the terminals will also be disrupted. Star network model is relatively simple, so widely used by the per-bank-right which usually has many branches scattered in various locations. With the configuration of these stars, then all sorts of activities that exist in the branch offices it can be controlled and coordinated well. In addition, education also tend to use a star network is to control the activities of their students.

Excess
· Damage to one channel will affect only the channel network and the station adrift.
· Security level is high.
· Resistant to a busy network traffic.
Addition and subtraction · station can be done easily.

Shortage
- If the node was destroyed, then the entire network will be stopped.
Handling
· The need for a backup center node set.

view star network :

3. Ring Networks
In this network there are several devices interconnected with each other and will eventually form the chart as well as a ring. Ring network does not have a point that acts as a central regulator or data traffic, all nodes have the same degree. The data sent will go through several nodes, so arrive at the destination node. In presenting the data, the network can move in one or two directions. Nevertheless, data exist to keep moving in one direction at a time. First, there is a message which will be delivered from point to another in one direction. When encountered a failure, for example, there is damage to existing equipment, existing data will be sent by way of a second, then the message is transmitted in the opposite direction, and ultimately could end up at the destination. Such configurations are relatively more expensive when compared with the star network configuration. This is due, any existing node will act as a computer that will overcome every application at hand, and must be able to share its resources on the existing network. In addition, this system is more suitable for systems that are not centralized (decentralized-system), which is not required the presence of a certain priority.

                                                         view of ring network

4. Tree Network
            In tree networks, there are several levels of nodes (node). Central or higher level node, another node can set a lower level. Data sent to the central node first. For example to move from computer to computer node node-3-7 as well as in the figure, the data must pass through node-3, 5 and node-6 before ending at the node-7. The better part network tree model like this is, can the formation of a group that is required at all times. For example, companies can form a group consisting of terminal accounts, as well as in the other group formed for the sale terminals. The drawback is, if the node that is higher then does not work, then the other group who are below it eventually also became ineffective. The workings of a tree network is relatively slow

                                           view of tree network

5. Bus Network
Another configuration is known as a bus-network, which is suitable for areas that are not too broad. Each computer (each node) will be connected by a communication cable through an interface. Each computer can communicate directly with the computer or other equipment that may be in the network, in other words, all nodes have equal footing. In this case, the network is not dependent on existing computers be centered, so if any of the equipment or one node is destroyed, the system can still operate. Each node that has no address or nature itself. So for access to data from one node, the user or wearer simply states the address of the node in question. Excellence is the development of a network bus topology or adding new workstations can be done easily without disrupting the other workstations. The drawback of this topology is when there is interference along the cable at the center of the whole network will have the disorder.

view of bus network

6. Plex Network (Network Combination)
Network is a truly interactive, where each node has the ability to directly access not only to computers, but also with a knot or other equipment. In general, this network has a shape similar to a star network. Organization of existing data using the de-centralization, is to perform maintenance, use the centralized facility.

view of plex network

Logical topology is generally divided form the two types, namely:

a. Topology Broadcast

In simple terms can be described is a host that sends data to all other hosts on the network media.

b. Token Passing Topologies

Set the data transmission on the host through the media by using a token that rotates on a regular basis throughout the host. Host can only transmit data only if the host has the token. By this token, collisions can be prevented.

a factors that deserve consideration for the selection of topology is as follows:
- New revenue
What are the most efficient systems are needed in the organization.
- Speed
To what extent is the speed required in the system.
- Environment
Such as electricity or factors - in other environmental factors, which affect the type of hardware used.
- Size
Up to how large the network size. Does the network need a file server or a dedicated server.
- Connectivity
Are the other users who use laptop computers to access the network from various locations.